Signaling system



July 13, 1948. A. PQ'MONTGOMERY 2,445,233

SIGNALING SYSTEM I Filed Sept. 1, 1944 Awe/A515 ac. [Mr/16:

F7 2- iwi? Wave af aa/hf J0.

WWAwwm/W r m/1 a Patented July 13 1 948 v 1,445,233 S'IGNALmGsiIs'rIJt/r I Pl lt Iontgoniery, Na 'rberthi "1 m; assigno'r, I bymeene assignm "ents, to 'Phllco Corporation,

Philadelphia; Pa; afcorporation' of Per'msyl- --vania.'

insta ts steamer 1, tote-(senate:

G'CIaims. (179+-'171.5)'

This to a" novelcircui't for d gian intermittent audio "signal whose fies ac'cording "to the nail to when the l'c'irtude of a control sig s'e instances "in which it is desired to conintelligence to a'listen'er as to some variable $9 .93 3 I principal object oi the invention; therefore,

lligenceto a listener by means of an t udio 'sig iial; whose frequency 10f I j g the Infediu'rnjby whichsuchiht'elliencefis; conveyed. Thispbj'ect is acc'ornplish'ed,

Ti l'ie' sii ixi ea by h ii e o tena le-i qu'en'cy voltage wave in the manner aboveindicated of'the invention to produce U I a ency sawto'oth voltage wave in the mannerfabove indicated.

oth j Objects and fe'aturesof the i rivention'will f ear 11a. M "Fig. 1' i s a schematic diagram of the novel cirprovid'ed by the; invention; end-'- 2 and 3 illustrate the vintage waves proi i ed brilt i refl Referring to Fig. 1, he'recta'ngle I Bre'pres'ents e- "vehi'ent sour eof variable D. Crcontiol ge wh'ose magnitude it desired to' indicate "andWhi'chmay represent somevariable condition. I

A sawtooth voltage generator I9 is controlled by the D. C.'-"c'b'ntrol'vo1tage so that the frequency of the generated sawtooth voltage wave varies "according to the magnitude of the control voltage. Thesawtooth voltage generator comprises a gas tube20 and its associated circuit elements. Thelatter include a condenser 2| in the cathode -?eircuit, the plate load resistor 22,- the potentiom- "eter:23x-and the by-Pass condenser 24,-;connected was shown; The sawtooth voltage wave is de- 55 velo ped across the condenser 2 l e Th -.(3- .qo iml vo ta wd vmlar resistor '25. The potentiometer 23 controls the operation of the sawtooth generator and is adjusted so as to cause the later to start oscillating "responsive. 'The invention-1e applicable-= vid'e hovel mee s; for conveying the dieee'ootdihg totheinvention, by" p doo'ing a volt-' t voltage wave of one polarity only, there-'" i t produce the desired? intelligence-com ittent audio signal byhtiliz'in hereinafter. In the accompanying draww and is applied to the cathode or tube 20 through at some chosen value ofthe D. C. control voltage. Preferably the adjustment of-potentiometer==i 23 'iich 'as to cause the sawtocth generator to start ill'at'ingwhen' the control voltage is at' its maximum amplitude. the amplitude of the control voltagedeorases; the'consequent lowering of the potential-on the cathode oi tube 20 causes a corresponding increase inthefrequency of the sawtooth voltagewave. Thus the frequency of the sawtooth voltage wave varies in inverse relation toth'e "nipljitud'eof the control voltage. The sawtooth ii'rator isso designed that its frequency'o'foscillation'is-low. lijorexample, its frequency-may[vary over arangeof about 1 to 10 s e i f en An audible "tone "signal of constant audio frequency e. 3.11000jcycl'e'gis supplied from a suitable Source' ZG and'is super mposed on the sawtooth volta'ge wave rheans'oi the. connection including elements 21*" 28 and "29. The resultant voltage wave (sho'w ihFi'g 2) "appearing at point 30 is suppli dto" control grid of a vacuum tube 3| by Way of-eou mig"condenser 32, which tube is biased so tha't' only the positive half of the wave is amplified and isjde'ri'ved fromthe plate circuit of the tub'e'by way or the output connection 33.

Thesi'ghal output-as shown in Fig. 3, issu'pplied tda suitable"sohndmeproducer; such asa loud speaker Knot shown) which emits an intermittent tone whose frequency of repetition indicates the amplitude of the control voltage.

s'ecohdvacuum tube 34 is connected to the 'grid cathode circ'uitof tube 3| as illustrated -A resistor 35, having an associated by-pass 'con- 'denser"36,"is connec ed between the cathode "of N I 3| and ground. The cathode end ofresis'tor through resistor 33 to a tap on resistor 35. By

- this arrangement, tube 3l is biased by the voltages across the upper part of resistor 35 and Tresi ro'ss "resistor 3 9, and the bias isdetermined by v ate current'of tube 34.

portion of the 13.0; control voltage across The .biasjofth is tube is controlled by means QpIetelY atany predetermined value of the control vol tag'e. "Within the-desired operating range .for which the potentiometer 4| isadjus'ted,"'the Ia'mplit'udeof'the control voltage will be sufficient- "l feineu so that the -'be cutbff and hence will not afiect the bias of plate current of tube 34'will tube 3|. But when the control voltage rises to the cut-off value, it will cause such an increase connected thi'o'ughrsiStoi 31 to'the s urc of plate supply.; The anode of tube 34 is coninected'to the grid resistor 38 and is also connected termined by the amplitude of the control voltage, the audible indication may be cut off when they amplitude of the control voltage reachessaid predetermined value.

is emitted at a rate corresponding to the amplitude of the control voltage. From the foregoing 4 according to the magnitude of said control voltage, a sourceof tone signal having a constant "audio' frequency higher than the frequency of When the control voltage is again below the cut-off value the audible signal.

description, it will be seen that the invention provides a novel indicator circuit which may be utilized where it is desired to indicate some condition. For example, the invention has been used in a radar system to indicate the range or distance of an object from the radar equipment.

In a particular embodiment of the invention,

the various circuit elements had the following values:

Resistor l547,000 ohms Condenser ll-1 mlcrofarad Condenser 2I.1 microfarad Resistor 22--68,000 ohms Resistor 23-200,000 ohms Condenser 24-.5 microfarad Resistor 25--2.2 megohms Condenser 21-.001 microfarad Condenser 28--.0l microfarad Resistor 29-150,000 ohms Condenser 32.05 microfarad Resistor 35--6,800 ohms Condenser 36.1 microfarad Resistor 3'l-68,000 ohms Resistor 381.5 megohms Resistor 39-470,000 ohms Resistor 4l-100,000 ohms Resistor 42--1,000 ohms Resistor 43-47,000 ohms Resistor 44-47,000 ohms Resistor l5-100,000 ohms While a single embodiment of the invention has been illustrated and described, it is not limited thereto but is capable of modification within the scope of the appended claims. a

I claim:

1. In a signaling system, means responsive to a control voltage for producing a low frequency sawtooth voltage wave whose frequency varies according to the magnitude of said control voltage, means for superimposing on said voltage wave an audio frequency signal voltage of higher frequency than said voltage wave, and means for selecting a portion of the resultantvoltage wave so as to produce an intermittent audio signal whose frequency of recurrence varies according to the magnitude of said control voltage.

2. In a signaling system, means responsive to a control voltage for producing a low frequency sawtooth voltage wave whose frequency varies according to the magnitude of said control voltage, means for superimposing on said voltage wave an audio frequency signal voltage of higher frequency than said voltage wave, and means for selecting the positive half only of the resultant voltage wave, whereby to produce an intermittent audio signal whose frequency of recurrence varies according to the magnitude of said control voltage.

3. In a signaling system, means responsive to a control voltage for producing a low frequency sawtooth voltage wave whose frequency varies said voltage wave, means for superimposing said tone signal on said voltage wave, an electron tube, means for applying the resultant voltage wave to said tube, and means for biasing said tube so that it transfers only the positive half of said resultant voltage wave, whereby to produce an intermittent audio signal whose frequency of recurrence varies" according to the magnitude of said control voltage.

4. In a signaling system, means responsive to a control voltage for producing a low frequency voltage wave whose frequency varies according to the magnitude of said control voltage, a source of tone signal having a constant audio frequency higher than the frequency of said voltage wave, means for superimposing said tone signal on said voltage wave, an electron tube, means for applying the resultant voltage wave to said tube, means for biasing said tube so that it transfers only the positive half of said resultant voltage wave, whereby to produce an intermittent audio signal whose frequency of recurrence varies according to the magnitude of said control voltage, and means responsive to said control voltage for rendering said tube incapable of transferring any part of said resultant voltage wave when the amplitude of said control voltage reaches a predetermined value.

5, A method of producing an intermittent audio signal whose frequency of recurrence varies according to the magnitu e of a control voltage, which comprises generating a low frequency sawtooth voltage wave, causing the frequency of said voltage wave to vary according to the magnitude of the control voltage, superimposing on said voltage wave an audio frequency signal voltage of higher frequency than said voltage wave, and selecting time-spaced portions of the resultant voltage wave so as to produce the desired intermittent audio signal.

6. In a signaling system, a source of variable unidirectional voltage whose magnitude is representative of some variable condition which it is desired to indicate, a generator of a low frequency voltage wave, means responsive to said unidirectional voltage for. varying the operating frequency of said generator according to the magnitude of said unidirectional voltage, means for superimposing on said voltage wave an audio frequency signal voltage of higher frequency than said voltage wave, and means for selecting a portion of the resultant wave with respect to a certain level, so as to produce an intermittent audio signal whose frequency of recurrence varies according to the magnitude of said unidirectional voltage.

ANDREW P. MONTGOMERY.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Hansell Dec. 28, 193'? 

